How to split module code into multiple sources ?

The module needs to be in a single file.

I believe there is a way still, since e.g. hierarchically the whole SDK is under the single module 'Toybox', and there is no way/I find it hard to believe the whole SDK is in a single file

FYI

Unless I am mistaken, the following seems to work:

file C1.mc:
module M1 {
    class C1 {
        ... // class code here
    } // end C1
}


file C2.mc:
module M1 {
    class C2 {
        ... // class code here
    } // end C2
}


optionally (i.e. not a must) in addition you could also have
file M1.mc:
module M1 {
    // some module-level code here
}

Does it compile and run this way?  If so, old dogs can learn new tricks!